The Dangers of Synthol and Other Muscle Site Enhancement Oils (SEOs)
If you've ever seen a bodybuilder literally "balloon up" in size overnight, you might be wondering how such a phenomenon is possible. Sure, pro-hormones, anabolic androgenic steroids (AAS), and selective androgen receptor modulators (SARMs) are powerful compounds that can contribute to serious increases in muscular size, but even those substances require weeks or months to yield full effects.
Some bodybuilders want radical increases in muscular size without the side effects of these compounds so they inject site enhancement oils (SEOs), the most popular of which being synthol, into their body.
History & Use of Synthol and Other Muscle Enhancement Oils
The use of site enhancement oils such as paraffin, sesame, and walnut oil has been documented as early as 1899 as a way to increase breast size and fill in wrinkles.   In the medical community, SEOs are now rarely injected except in the case of using sesame oil as a solvent for intramuscular gold injections to treat rheumatoid arthritis. 
However, SEOs have remerged in popularity as an alternative to steroids for those looking to increase muscle size. Both SEOs and steroids are directly injected in to the muscle belly. However, SEOs offer immediate enlargement effects whereas the effects of steroids still require the application of hard work in the weight room and disciplined nutrition in the kitchen.
The most popular SEO in the bodybuilding community, synthol, was developed in the mid-1990s by the German bodybuilder Chris Clark.  Mr. Clark developed synthol with the goal of being longer-lasting, more stable, safer, and less allergenic than other SEOs.
Unlike other site enhancement oils, synthol is a blend of three ingredients - 85% oil (usually medium chain triglycerides), 7.5% lidocaine (local anesthetic/painkiller), and 7.5% benzyl alcohol (disinfectant/sterilizer).  Mr. Clark chose a non-allergenic oil mixed with two ingredients used to minimize instance pain, discomfort, and infection.
Regarding the cost of SEOs, look no further than popular online stores for paraffin oil, or your local health foods store for sesame and walnut oil at the lowest prices. Synthol is a bit trickier to find in brick and mortar stores, but like anything, it can be found online.
Bodybuilders and Synthol OilBodybuilders tend to use synthol on smaller muscle groups like the triceps, biceps, deltoids, and calves because it's typically more apparent. These muscle groups are undeveloped and require less synthol to bring up compared to larger muscle groups like the back, chest, and thighs. In fact, injecting synthol in the biceps and triceps has become widespread enough to warrant a nickname for the act - fluffing. 
Users typically inject synthol into each muscle head of a muscle group; two locations in the biceps (short and long heads) and three locations in the triceps (lateral, long, and medial heads). Unless you specifically know the lagging muscle head, failure to inject synthol in the proper area could lead to an even more disproportionate physique.
Synthol Side Effects & DangersWhile injecting SEOs like synthol may not have the typical side effects associated with using pro-hormones, AAS, or SARMs, they still carry a number of serious dangers. Before we delve in to the horror stories, below is a list of possible side effects from injecting SEOs:     
- Localized redness, swelling, pressure, and pain in and around the injected muscle group(s). If lumps do form, one site recommends immediately stopping SEO injection, massaging the lumpy area until it disappears, and then continue injecting immediately as desired. 
- Deformed and unnaturally shaped muscles
- Purpuras - occur when small blood vessels leak blood under the skin. 
- Nerve damage
- Skin ruptures
- Complete halt of natural muscle regeneration
- Induration/Sclerosis - hardened patch[es] of tissue in the skin or mucous membranes. 
- Abscesses - a collection of pus in any part of the body that, in most cases, causes swelling and inflammation around it.
- Cysts - a closed pocket or pouch of tissue filled with air, fluid, pus, or other material.  May be named according to the injected material (e.g. paraffinoma as a result of injecting paraffin).
- Cystic scar tissue.
- Pulmonary Artery Occlusion - the blockage or closing of the artery that carries blood from the heart to the lungs.  Can be caused by or as a result of injecting SEOs.
- Vacuolation - the formation of vacuoles in cellular tissue, which leaves small extracellular cavities or spaces within tissues and creates a "Swiss cheese" pattern within the muscle. 
- Vasculitis - the inflammation of blood vessels
- Sclerosing Lipogranulomatosis - "subcutaneous inflammatory and fibrosing reaction occurred with regional lymphadenopathy [re: irregular lymph nodes]. 
- Fistulas - abnormal connection[s] between an organ, vessel, or intestine and another structure.
- Fibrosis - the thickening, stiffening, and scarring of connective tissue. 
- Hard Oedema - the hardening of fluid build-up in body tissue. 
- Lymphangitis - infection of the lymph vessels throughout the body; typically caused by complications from bacterial infections. 
- Cerebral stroke -blood flow (oxygen and nutrients) to all or part of the brain ceases
- Myocardial Infarction/heart attack - blood flow (oxygen and nutrients) to all or part of the heart ceases.
Synthol Horror Stories
If you're not yet convinced of the dangers of injecting SEOs, there are numerous clinically documented horror stories, which we will discuss in this section.
The first of which involves a 40-year-old male amateur bodybuilder who self-injected sesame oil for 8 consecutive years. His right upper arm became infected and he experienced painful reddened swelling that prevented him from weightlifting. Doctors performed an MRI and found 100 intramuscular oil cysts which required 2-step septic surgery.
During surgery they found almost no normal muscle in the upper right arm as well as pus-filled cystic scar tissue. Even one year after surgery an MRI revealed no natural muscle regeneration in the right upper arm area. Furthermore, it took over three years before the patient no longer experience exceptional pain in this region and was able to resume his normal weight training activities. 
Our second story follows a male amateur bodybuilder who used 10 injections of paraffin oil into his arm over the course of about 1.5 years. He came to doctors complaining of exceptional muscular pain, malaise, a high body temperature, as well as swelling in and around the injection muscle. He had enlarged lymph nodes in his neck, blood measurements indicating infection, and numerous small cysts throughout the bicep and tricep muscles.
During this visit doctors did not find abscesses or fistulas and decided not to perform surgery due to the extensive spread of the paraffin oil throughout the muscles. 1.5 years later the patient returned after self-administering compression therapy to expedite wound healing but he still have multiple firm tumors on both his arms and on his chest.
These tumors were likely the result of the body's defense mechanism to the foreign paraffin oil and the oil spread outside of the originally injected area. Because the oil spread so much the doctors hesitated to perform surgery and instead encouraged the patient to continue with compression therapy as it appeared to be working.
This was the first clinically documented instance of using compression therapy to treat the side effects of injecting SEOs. Doctors proposed that the compression decreases the distance between capillaries and skin, improves nutrition and oxygenation, as a result expedites wound healing and decreases inflammation. 
Our third story details a 29-year-old male amateur bodybuilder who experienced severe muscle pain in his upper right arm five years after his friend injected 3mL of Synthol in to both biceps, four times per week for four consecutive weeks. In addition to visually deformed muscles, he had extensive fibrosis, vacuolation, and swelling, as well as numerous cystic fatty lesions. Similar to our previous story, this user had no regular muscle tissue in this area but rather only had fibrotic scar-like tissue. 
Our next two stories are brief but also speak to the dangers of injecting SEOs. A 48-year-old male self-injected sesame oil in to his pectoral muscles and began noticing subcutaneous nodules 9 months after injection. Doctors found round nodular cysts up to 1cm in diameter, full with oily material and surrounded by inflamed tissue, in both pectoral regions. 
A 21-year-old bodybuilder self-injected 10mL of sesame oil in to both biceps six times before he went to the hospital to complain of extreme muscle pain and purpuras in and around the injection site. Doctors performed an MRI and found extensive oedema, vasculitis, and cell inflammation. Interestingly enough, doctors were able to treat and "cure" this patient over 4 weeks, consisting of a 2-week regimen of oral corticosteroids and an as-needed high-dose morphine injections to control pain. 
Final ThoughtsIt's the author's opinion that you avoid SEOs at all costs as they shortcut hard work, eliminate the need for dedication, have numerous side effects, and are easy to improperly use. If you have experience with SEOs, agree or disagree with the information provide, or have questions/comments/concerns, leave a comment below!
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